Mary Costello (née Scanlan) (6 January 1839 – 18 December 1924) was a pioneering pastoralist in the Northern Territory of Australia.
Costello was born in County Clare in Ireland, the daughter of Patrick Scanlan and his wife.
After immigrating to Australia in 1861,[1] she married John Costello at Grabben Gullen in New South Wales on 7 January 1865.
They had two sons before leaving New South Wales for Kyabra Creek in western Queensland.
After a year in Ireland, Mary settled her daughters into a convent in Townsville.